The invention relates to a device for purifying fuel vapours filled in a fuel tank and a filler pipe of an internal combustion engine powered vehicle, through a hole formed in the tank upper wall to be conducted into a canister for vapours recovery and clarification. More particularly it relates to such device in which a valve normally closing said hold is adapted to be automatically open in reply to insertion of a fuel dispensing nozzle into the filler pipe.
The fuel for the internal combustion engine is of a lower boiling point so as to be vaporized more or less in the fuel tank and the filler pipe. When the cap closing the open end of the filler pipe is disengaged therefrom for refuelling, fuel vapours filled therein are expelled as the fuel surface is raised and released in the atmosphere. This is not desirable in view of protection of environment and saving useless loss of energy.
In order to solve the problems referred to above, some proposals have been made by allowing fuel vapours to be expelled out of the fuel tank through a hole formed in the fuel tank upper wall during refuelling to be burned in the internal combustion engine through a canister containing for instance activated carbon and a carburetor, e.g. U.S. Pat. No. 3,957,025.
However, this is not satisfactory in view of a complexity of the system and troublesome actuation.
In U.S. Pat. No. 4,715,509 owned by the assignees of the present patent application, a fuel filler pipe provided with a mechanism adapted to open a hole connected to the internal combustion engine via the canister and the carburetor and normally closed by a valve when inserting the fuel dispensing nozzle into the filler pipe to open a flap provided near to the open end thereof is disclosed.
This is still unsatisfactory in view of a fairly many parts to be assembled.